The present invention relates to a pneumatic yarn splicing apparatus for splicing spun yarns.
Pneumatic yarn splicing processes are advantageous over a prior process of knotting yarns together in that since there is no knot at the spliced ends, the spliced yarns present reduced resistance to their movement through yarn guides and are less liable to be broken in subsequent steps, and the spliced ends cannot easily be found in final textile products.
Various pneumatic yarn splicing devices have been proposed so far. According to Japanese Patent Publication No. 56-47108, yarn ends are untwisted in nozzle pipes prior to yarn splicing, and the yarns are spliced under a stream of compressed air while they are arranged in the nozzle pipes with distal ends attracted by streams of suction air with the other ends fixedly held. Such a yarn splicing process produces sightly spliced yarn ends which are of an increased strength and thus practical in use. With the disclosed process, the yarn ends passing through a yarn splicing hole and untwisted by streams of air in the nozzle pipes are disposed one on each side of the yarn splicing hole. The yarn ends thus untwisted are drawn out by levers, and the yarns are spliced while the distal ends of the yarn remain adjacent to openings of the nozzle pipes by the action of the suction air streams. As described in the above publication, attracting and retaining the yarn distal ends with the suction air streams is more advantageous than means for mechanically holding yarn ends in that the yarns as spliced remain flexible, and the yarn ends become sufficiently entangled with each other leaving no angular yarn ends. Since yarn splicing due to compressed streams of air takes place around the yarn splicing hole, the openings of the nozzle pipes are located as closely to the yarn splicing hole as possible because the yarn distal ends sufficiently spaced from the yarn splicing hole would not be preferable. The yarn distal ends are attracted and held by the suction air stream in the vicinity of the openings of the nozzle pipes with the yarn ends remaining slightly within the nozzle pipes.
The yarn ends are pulled out by the levers to bring the yarn ends sufficiently attracted and untwisted in the nozzle pipes to the foregoing condition.
Where core spun yarns having resilient cores of polyurethane are employed, the yarn ends as they are drawn out become abruptly displaced under their own resiliency by the action of the suction air stream in the vicinity of the nozzle pipe openings, with the result that the yarn ends tend to get spliced within the yarn splicing hole while they are sagged.